A diver has to know various parameters when he makes an underwater dive in order to ensure his safety. In particular, the diver must be able to know instantaneously at what depth he is in order to avoid the risk of exceeding the pre-established maximum dive depth. The diver must also know his dive time to avoid exhausting his oxygen reserves and so that he can come back up to the surface in complete safety. Watches that provide a diver with information relating to his instantaneous depth and dive time are already known.
However, there is an additional parameter which, to the Applicant's knowledge, is not taken into account by dive watches available on the market. This parameter is linked to the stability of the diver's depth when he makes a decompression stop. Indeed, it is known that the body absorbs the nitrogen contained in the air breathed in by divers, in particular into the bloodstream, in a proportion that increases with the ambient pressure and duration of immersion. It is imperative for this nitrogen to be eliminated by the body before the diver returns to the open air. If the nitrogen is not eliminated, the diver runs a risk of serious danger, or even death. The problem of eliminating nitrogen has been solved by requiring divers to observe very slow ascent speeds to the surface and, especially, to make decompression stops at certain depths. During these decompression stops, the difference that exists between the ambient pressure and the blood pressure causes nitrogen dissolved in the blood to pass outside the body. By observing these decompression stops, the diver thus gradually succeeds in eliminating the nitrogen dissolved in his blood. However, nitrogen is eliminated all the more efficiently if the diver succeeds in remaining at a stable depth in the decompression stop that he is making. There therefore exists a need in the state of the art for a watch that can indicate depth fluctuations to the diver when he is making a decompression stop.
It is an object of this invention to respond to this requirement by providing a mechanical or electromechanical dive watch including hour and minute hands, this watch being characterized in that it further includes a depth indicator hand and a depth variation indicator hand, the depth indicator hand providing the diver with an instantaneous indication of his depth when he is diving, the depth variation indicator hand being at that moment locked at zero, the depth indicator hand being in turn locked when the diver reaches a decompression stop that he has to make and the depth variation indicator hand being released to indicate to the diver any depth variations relative to the decompression stop depth, the depth variation indicator hand being then returned to zero and locked whereas the depth indicator hand is released and again indicates the exact dive depth when the diver resumes his ascent.